Setting width only on post featured image

WordPress allows you to set a featured image for a post or a page. You can call this featured image (thumbnail) in the loop, but you are restricted to how the thumbnail is sized. The options range from the default thumbnail size (150×150), but this cuts off part of the image. The rest of the options are the standard sizes: medium, large, and original size. The other option is to set your height and width using an array.

Recently I was tasked with posting either the thumbnail or the excerpt from a post, but the space where the loop was placed is limited in width. Since you cannot declare just a height *or* just a width, I had to find a work-around to avoid distorting the thumbnail.

#blog article img {
width: 170px;
height: auto;
}

Usually I would set just the width on the actual image itself, but since I don’t have access to the raw HTML, I had to simply use the CSS to define my dimensions. Set the width to what I want and set the height to ‘auto.’ This will resize the height automatically to retain the dimensions of the image while still resizing it to the desired width. Easy enough.